1. Field of the Invention
This invention relates to a method and apparatus for adjustably positioning a part relative another part.
2. Description of the Related Art
Mechanical assemblies often include parts or subassemblies that are positioned relative to one another, and, in certain situations, it is desirable for these parts or subassemblies to be adjustably positioned relative to one another. In other words, it may be desirable for a position of a part to be adjustable relative to a feature of another part. For example, as illustrated in FIG. 1, a rail 100 may be attached to a base 102 via supports 104, 106, 108. The rail 100, as illustrated in FIG. 1, is not straight, i.e., the rail 100 is not parallel to a straight reference line 110. Accordingly, as a carriage 112 travels along the length of the rail 100, a distance from a top surface 114 of the carriage 112 to the reference line 110 varies, as illustrated by distances D1A, D1B and D1C. Further, an angle between the top surface 114 of the carriage 112 and the reference line 110 varies, as illustrated by angles a1A and a1B.
Typically, the situation illustrated in FIG. 1 is not acceptable, as it is usually desirable for the distance between the top surface 114 of the carriage 112 and the reference line 110 to be constant, within a predetermined tolerance, as the carriage 112 travels along the rail 100. Further, it is generally desirable for the angle between the top surface 114 of the carriage 112 and the reference line 110 to be constant, within a predetermined tolerance, as the carriage 112 travels along the rail 100.
The ease of adjusting the rail 100 so that it is substantially parallel to the reference line 110 in the plane of FIG. 1 is generally related to the means used to attach the rail 100 to the base 102. FIG. 1 illustrates two ways of attaching the rail 100 to the base 102. Supports 104, 106 are one-piece supports that include a flange 116. The supports 104, 106 may be attached to the base 102 via a fastener 118 through the flange 116 and into the base 102. Support 108 includes an upper portion 120 that may be attached to the rail 100 and a lower portion 122 that may be attached to the base 102 via a fastener 124 through a flange 126. The upper portion 120 may be attached to the lower portion 122, for example, by a fastener 128 and pins 130.
FIG. 2 illustrates a conventional method of adjusting the supports 102, 104, 106 to straighten the rail 100. A shim 200 may be placed between the flange 116 and a top surface 202 of the base 102 to straighten the rail 100 near the support 104. The thickness of the shim 200 raises the support 104 so that the distance D2C from the reference line 110 to the top surface 114 of the carriage 112 when the carriage 112 is above the support 104 is substantially equivalent to the distance D2B from the reference line 110 to the top surface 114 of the carriage 112 when the carriage 112 is above the support 106. To adjust the support 108, the fastener 128 and the pins 130 may be removed from the support 108 and the upper portion 120 of the support 108 may be moved downwardly relative to the lower portion 122 of the support 108 to straighten the rail 100 near the support 108 so that the distance D2A from the reference line 110 to the top surface 114 of the carriage 112 when the carriage 112 is above the support 108 is substantially equivalent to the distance D2B from the reference line 110 to the top surface 114 of the carriage 112 when the carriage 112 is above the support 106. New holes (not shown) for the fastener 128 and the pins 130 may then be match-drilled into the upper portion 120 of the support 108 and the lower portion 122 of the support 108. The upper portion 120 of the support 108 and the lower portion 122 of the support 108 are then fastened together by the fastener 128 and the pins 130.
Over time, it is common for the rail 100 to again become misaligned with the reference line 110 due to forces imparted on the rail 100; supports 104, 106, 108; and the base 102. Thus, it is also common for adjustments to be made periodically to the rail 100 to realign the rail 100 with the reference line 110. In the example illustrated in FIG. 2, a new shim 200 may be required that has a different thickness. Depending upon the positioning accuracy required, the shim 200 may have a very precise thickness tolerance, requiring the shim 200 to be machined using costly, time consuming processes. Further, as new holes are generally required for the fastener 128 and pins 130 each time the support 108 is adjusted, structural integrity of the support 108 may be compromised. It is also common for a series of adjustments to be made to the rail 100 during an adjustment procedure before the straightness of the rail 100 is deemed to be within tolerance. Each time an adjustment is made, a new shim 200 may be required and new holes for the fastener 128 and the pins 130 may be required, further amplifying the difficulties discussed above.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.
In one aspect of the present invention, a position-adjustable fastening apparatus capable of maintaining a position of a first member with respect to a second member is presented. The first member defines a bore therein and the second member defines a bore therein. The position-adjustable fastener includes a cam receiver defining a grooved bore therein and including a plurality of bearing surfaces, wherein the plurality of bearing surfaces are unequally spaced from a center of the bore of the cam receiver, and the cam receiver is disposed in the bore of the first member such that at least two of the plurality of bearing surfaces are proximate the wall of the bore through the first member.
The position-adjustable fastener further includes a cam defining a bore therethrough and including a grooved outer surface, wherein the bore through the cam is eccentrically spaced from the grooved outer surface, and the cam is disposed in the opening of the cam receiver such that the grooved outer surface meshes with the grooved bore of the cam receiver. The position-adjustable fastener further includes a fastener, wherein the fastener is disposed in the bore through the cam, and the fastener engages the bore through the second member.
In another aspect of the present invention, a position-adjustable fastening apparatus capable of maintaining a position of a first object with respect to a second object, is presented including a first member defining a bore therein, wherein the first member is joined to the first object and a second member defining a bore therein, wherein the second member is joined to the second object. The position-adjustable fastening apparatus further includes a cam receiver defining a grooved bore therein and including a plurality of bearing surfaces, wherein the plurality of bearing surfaces are unequally spaced from a center of the bore of the cam receiver, and the cam receiver is disposed in the bore of the first member such that at least two of the plurality of bearing surfaces are proximate the wall of the bore through the first member.
The position-adjustable fastening apparatus further includes a cam defining a bore therethrough and including a grooved outer surface, wherein the bore through the cam is eccentrically spaced from the grooved outer surface, and the cam is disposed in the opening of the cam receiver such that the grooved outer surface meshes with the grooved bore of the cam receiver. The position-adjustable fastening apparatus also includes a fastener, wherein the fastener is disposed in the bore through the cam, and the fastener engages the bore through the second member.
In a further aspect of the present invention, a method for fastening a first member and a second member is presented. The method includes positioning the first member with respect to the second member, orienting a cam receiver with respect to a bore in the first member, placing the cam receiver in the bore in the first member, orienting a cam with respect to a bore in the cam receiver, placing the cam in the bore in the cam receiver, and engaging the fastener with the second member through the bore in the cam.
In yet a further aspect of the present invention, a position-adjustable fastening apparatus capable of maintaining a position of a first member with respect to a second member is presented. The position-adjustable fastening apparatus includes a cam receiver disposed in a first bore defined by and extending into the first member, the cam receiver including a plurality of bearing surfaces unequally distanced from a center of a grooved bore defined by and extending into the cam receiver, the bearing surfaces being positioned proximate the wall of the first bore and a cam disposed in the grooved bore of the cam receiver, the cam defining a second bore therethrough and including a grooved outer surface meshing eccentrically spaced from a center of the second bore, the grooved outer surface meshing with the grooved bore of the cam receiver. The position-adjustable fastening apparatus further includes a fastener disposed in the second bore defined by the cam and engaged with third bore defined by the second member.